1. Field of the Invention
This invention relates to a ball and socket type joint of the type used in vehicular steering and/or suspension applications, and more particularly toward such a ball joint assembly for use in applications where one of the anchoring members, such as a steering knuckle or tie rod for example, is made from a relatively soft material like aluminum.
2. Related Art
Ball joints are typically used in vehicular applications where three-dimensional movement of a wheel, and in particular a steerable wheel, is required when a vehicle is turning and the suspension is accommodating movement over rough terrain. In the normal course of operation, ball joints are subjected to very high stresses. These stresses are transmitted through the stud of a ball joint assembly into the suspension member, which may be a steering knuckle, control arm, steering link, frame member or other feature.
The recent emphasis on reducing vehicular weight is driving material selections toward lighter options. Sometimes, there is a motivation to substitute aluminum for traditional cast iron materials, even in the area of chassis and suspension components. Unfortunately, lighter materials are often softer than the heavier materials they replace, and therefore less suited to endure the localized and concentrated stresses which may arise during normal vehicular operations.
FIGS. 9 and 10 illustrate two different prior art attempts to accomplish similar functionality for ball joint assemblies, and in particular studs which are intended to be anchored in relatively soft material like aluminum. FIG. 9, in particular, is intended to correspond to the design depicted in U.S. Pat. No. 6,527,468, the entire disclosure of which is hereby incorporated by reference. These designs are either difficult to produce on a high volume basis, or result in unacceptable attributes such as NVH issues and provide less surface-to-surface contact in the interface regions. By contrast, the subject invention as depicted in various embodiments in FIGS. 1-8, overcomes some or all of these issues and represents a significant improvement over prior art constructions.
Accordingly, there is a need for an improved method of interconnecting a ball joint assembly to vehicular steering and suspension features to accommodate the anchor points being made from a softer material.